<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>返回顶部</title>
    <style>
        .container>p {
            height: 2400px;
        }

        .backToTop {
            width: 54px;
            height: 54px;
            background: #f1f1f1;
            text-align: center;
            color: #333;
            position: fixed;
            bottom: 20px;
            right: 20px;
            font-size: 14px;
            cursor: pointer;
        }

        .backToTop:hover {
            background: #ccc;
        }
    </style>
</head>
<body>
    <div class="container">
        <p>
            this is some details about the page!
        </p>
        <div class="backToTop" id="backToTop">
            返回顶部
        </div>
    </div>


    <script>
    
        let backToTop = document.getElementById("backToTop");

        backToTop.addEventListener('click',function () {
            
        },false);

    </script>
</body>
</html>